MBMS (Multimedia Broadcast Multicast Service) is used to provide a multimedia broadcast service and a multimedia multicast service for user equipment (UE) in a cell. The multimedia broadcast service may broadcast multimedia video information to all UEs. The multimedia multicast service may send some paid multimedia video information to a group of subscribed UEs for watching.
In an LTE (Long Term Evolution) system, when an MBMS mode is used to transmit a physical multicast channel (PMCH), a network side device transmits, on an MBMS point-to-multipoint control channel (MCCH), a modulation and coding scheme (MCS) index for an MBMS point-to-multipoint traffic channel (MTCH). Different MCS indexes correspond to different MCS configuration information. The configuration information includes a modulation scheme used when a transmitted MTCH is modulated and encoded, such as quadrature phase shift keying (QPSK) modulation, 16 quadrature amplitude modulation (QAM), or 64 QAM. A UE demodulates the received MTCH according to the configuration information.
Because of relatively poor environment quality (a relatively low signal-to-noise ratio) of a channel between cell-edge UE and a base station, to ensure service transmission robustness, when service data is transmitted to the cell-edge UE, a low-order modulation and coding scheme such as QPSK needs to be used. Because of relatively good environment quality (a relatively high signal-to-noise ratio) of a channel between cell-center UE and a base station, when service data is transmitted to the cell-center UE, a high-order modulation and coding scheme such as 16 QAM or 64QAM may be used to improve a signal transmission bit rate. In the LTE system, when MBMS data is broadcast to all UEs within the cell, to ensure that both the cell-center UE and the cell-edge UE can receive the MBMS data, only the low-order modulation and coding scheme can be selected. In this way, an overall system throughput is reduced, and system spectrum utilization efficiency is relatively low.